The invention pertains to processes and devices for coloring hair and, more particularly to a hair color dyeing process which utilizes a heating device to reduce the time required to dye the hair.
Processes for applying color-altering materials, such as dyes, to hair for the purpose of temporarily or permanently changing hair color are well-known in prior art. Typically, the color of hair can be altered through the use of rinses, sprays, lotions or creams. When darkening hair, the coloring material usually taken the form of a dye. Regardless of the coloring material used, it is applied in a step-by-step manner, often requiring a long waiting period to allow the chemicals in the coloring material to react and for the materials to bond with the hair.
Hair that is dyed retains its color until the color is chemically removed by bleaching or other like processes. The hair dyeing process is typically conducted at alkaline pH 9 to 10, requires 20 to 40 minutes, and usually employs hydrogen peroxide as an oxidizer. Consumers generally have their hair dyed periodically, typically once a month, sometimes as often as twice a month.
It is well known that when hair is treated with peroxide or other oxidizers, an essential amino-acid called cystins, which is found in hair, undergoes oxidation to cysteric acid. This chemical reaction leads to a weakening of the hair structure, making the hair dryer and prone to breakage. Accordingly, there is reason for consumers to believe that exposure to hydrogen peroxide during the dyeing of hair is a primary causative factor responsible for damaging the hair.
Damage to hair after a single dye application from such compositions, may be small. However, when dye applications are repeated, or when combined with other cosmetic treatments, such as permanent waving, relaxing, or bleaching, hair damage can be considerably more severe. Such damage is normally experienced by the consumer in the form of dry and brittle hair which has a tendency to break-off.
The hair coloring industry has attempted to satisfy the consumer concern or reformulating hair dyes with a metal ion catalyst that hastens the peroxide oxidation reaction of the dye precursors. This reformulation reduces the amount of time hair is exposed to the damaging effects of hydrogen peroxide or other oxidizers. However, these catalytic oxidative dyeing processes have met with little or not commercial success.
Against this background of known technology, the applicants have developed a new, faster, more efficient, and cost-effective hair dyeing process which utilizes heat and that can be performed outside the confines of a hair salon.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention. However the following U.S. patents, which do not disclose a heat application means, are considered related:
The U.S. Pat. No. 5,843,193 discloses a composition for oxidatively dyeing hair. The composition comprising, by weight of the total composition, 0.001-20% of at least one primary intermediate and at least one coupler for the formation of oxidation dyes, 0.01-10% of a 2-hydroxphenyl benzotriazole compound which absorbs ultraviolet radiation in the wavelength range of 0.5-20% surfactant, and 10-65% water; a two component kit containing the hair dye composition and a developer, and a process for oxidatively dyeing the hair for a time period ranging from 2 to 60 minutes.
The U.S. Pat. Nos. 5,316,551 and 5,100,438 patents disclose a method for oxidatively dyeing hair. A pre-treatment consists of contacting hair with an aqueous solution of an effective amount of particular metal/chelate complexes, and is followed by a treatment with an oxidative dye mixture. The process serves to conform the oxidative dyeing rate of virgin hair to that of the normally noncongruent rate of nonvirgin hair, so as to enhance the efficiency of the oxidative dyeing process without reducing the intensity or variety of the color.
The U.S. Pat. No. 4,935,032 discloses a process for dyeing human hair. The process utilizes the steps of applying to hair a composition the temperature of which is higher than 30xc2x0 C. and lower than 50xc2x0 C. The application of heat increases the solubility of the nitro dyestuff in the composition. The composition contains at least one nitro dyestuff of the benzene series, supersaturated relative to its solubility limit at ambient temperature in a cosmetic medium suitable for dyeing heir. The composition is chosen from the dyestuffs having a ratio KC lim greater than 2 its aqueous solution. The KO lim is the ratio of the limiting concentrations of the dyestuff in an aqueous medium which are measured at 50xc2x0 C. and 18xc2x0 C. the composition is maintained in contact with the hair either at ambient temperature or at a temperature above room temperature and below 50xc2x0 C.
The U.S. Pat. No. 4,279,613 discloses a hair coloring composition and a method for using the composition. The composition includes a coupler substance, customary couplers and a compound of the formula ##STR1##. The novel couplers are more physiologically suitable for use in hair colors and allow for the preparation of compositions which lead to highly stable colorings over a broad range of shades and tones. After the hair dye is applied the mixture is allowed to react for 30 minutes at 40xc2x0 C.
For background purposes and as indicative of the art to which the invention is related, reference may be made to the remaining cited patents.
When dyeing the hair, in general, the longer the hair dyeing process takes, the greater the risk that the air will be damaged. Conversely, the shorter the time period the less risk there is that hair damage will occur.
Current hair dyeing processes are widely used for permanently coloring hair. They are simple and convenient to use, low cost and safe, but unfortunately, they are also relatively slow when compared to the hair dyeing process disclosed herein which utilizes heat to xe2x80x9cspeed upxe2x80x9d the hair dyeing process. When heat is applied, the speed of the chemical reaction involved in the dyeing process is increased. The higher the temperature applied the quicker the chemical reaction which, in turn, minimizes hair damage.
The applied temperature functions by having a major effect on the dye reaction rate. Typically, for a common organic reaction when reactant concentrations are held constant, the rate nearly doubles with each rise in temperature of 10xc2x0 C. In fact, for many reactions near room temperature, an increase of 10xc2x0 C. causes a doubling or tripling of the rate. If concentration-time data is collected for the same reaction run at different temperatures, and the rate constant is solved, we find that k increases as the temperature (T) increases. In other words, temperature affects the rate by affecting the rate constant. A plot of k vs T gives a curve that increases exponentially, as shown in the Arrhenius Equation:
k=Ag-Ea/RT
where k is the rate constant, e is the base of natural logarithms, T is the absolute temperature, and R is the universal gas constant. The Ea term is the activation energy of the reaction, which Arrhenius considered the minimum energy that molecules must have to react. This negative exponential relationship between temperature and the rate constant means that as the temperature increases, the negative exponent becomes smaller; and therefore the value of k becomes larger, which means that the rate increases:
Higher Txe2x86x92Larger kxe2x86x92increase rate.
The examples below are given to further illustrate the effect of temperature on the dyeing process. Two of the applicant""s products and two products made by Clairol and L""Oreal were tested. For comparison purpose, a relative scale from 0 to 100 was used to quantify the intensity of the resulting color applied to the hair. The larger the number, the more intense the color.
The following dye composition made by the applicant produces a brown-block color when applied to pre-bleached light-brown color hair:
A specimen of pre-bleached, light-brown color hair was treated with the above-described dye composition for 5, 10, 15, 20, 25 and 30 minutes in different temperatures. For the test accuracy and consistency, the treated hair specimens were put in beakers which remained in a water bath in which the temperature was controlled at 20, 30 and 40xc2x0 C. respectively. The test results for Example I follows:
From the above data, it can be seen that a color intensity of 90 was attained in 30 minutes at 20xc2x0 C. But the same color intensity of 90 was also reach in 15 minutes at 30xc2x0 C. and in 5 minutes at 40xc2x0 C.
In a temperature test, at an ambient temperature of 22xc2x0 C., the average temperature in a human hair area (4 to 1.5 cm over the scalp skin) is 25xc2x0 to 28xc2x0 C. The temperature of the hair dye composition is as high as the ambient temperature. The temperature in the hair area becomes 24.2xc2x0 to 24.9xc2x0 C. after the hair dye is applied on the hair. The tests conducted indicate that the temperature in the hair area would easily increase to 30xc2x0 to 37xc2x0 C. if a hand-held, hot-air blower was used to apply hot air to the dyed hair for three to give minutes after which a plastic, disposable, shower cap is placed around the head to retain the heat for the required time. The test indicated that the covered shower cap can maintain the temperature in the hair area between 29.5xc2x0 to 31.5xc2x0 C. for at least 30 minutes.
Alternatively, a plastic shower cap can be placed around the head after the hair dye is applied to the hair and then covered with a hot, moistened towel to apply heat to the hair. The towel was vetted with 50xc2x0 to 55xc2x0 C. warm water and then placed over the shower cap. With this alternative method, the temperature in the hair area inside the shower cap increased to 36xc2x0 to 42xc2x0 C. in 1 to 2 minutes. If the towel is removed but the shower cap is keep on, the temperature in the hair area can be maintained at 30xc2x0 to 35xc2x0 C. for at least 30 minutes.
Experiments confirm that a hair dyeing process utilizing a hair dye in combination with the above heat application means can attain the required hair color in a much shorter time than is possible with no heat applied. For example, at an ambient temperature of 20xc2x12xc2x0 C. the applicant""s composition requires at least 30 minutes to dye the hair with a color intensity of 100, but it only needs 10 to 15 minutes to attain the same color intensity with the above mentioned heat application means.
The following dye composition made by the applicant produces a bright burgundy color when applied to pre-bleached light-brown color hair:
A specimen of pre-bleached, light brown color hair was treated with the above-described dye composition for 5, 10, 15, 20, 25 and 30 minutes in different temperatures. The test results for Example II follows:
For the Example II composition, to attain a color intensity of 80 at 20xc2x0 C. the hair dye must remain on the hair for a time period of 30 minutes, but at 40xc2x0 C. a color intensity of 90 can be attained in 5 minutes.
In practice, at an ambient temperature 20xc2x0 C.xc2x12xc2x0 C., the composition of Example II requires 40 minutes to dye the non-bleached hair from a dark color to the bright burgundy color. However, experiments indicate that the Example II composition can dye the non-bleached hair from a black color to a bright burgundy color in only 20 minutes, if the above heating process is applied.
The same tests were performed with the hair dye products; 48 True red color may by Clairol, and RR04 dark red color may be L""Oreal, respectively.
Clairol advises that it may be necessary to leave the hair color on for a total of 30-45 minutes to dye the hair to the desired color. Experiments indicate that only 15-20 minutes is needed to dye the hair to the required color with the products made by Clairol and L""Oreal, if the above heating process is applied. As a result of the above example, it can be seen that the application of heat is an effective method for minimizing hair damage and improving the hair dyeing efficiency.
In the above examples, the coloring agents must be toxicologically and dermatologically suitable for such use, and they must achieve a coloring of the desired intensity. It is also necessary that when combining a developer and coupler components a broad color spectrum can be achieved. Further requirements include good tolerance to light, permanent wave treatments, acid and rubbing. The hair coloring should remain stable over a period of at least 4 to 6 weeks without negative influence from light, rubbing and chemical agents. Besides the three reactive componentsxe2x80x94primary dye intermediates, color couplers and oxidizers, an oxidative dye composition may contain thickening material, and reducing agents.
The composition can be thickened with, for example, sodium aliginate, gum arabic, cellulose derivatives such as methylcellulose, hydroxyethycellulose, htdrocypropyl-methyclellose and carbocyethylcellulose, and various materials, such as oleyl alcohol, stearyl alcohol, cetyl alcohol, behenyl alcohol, and 1-docosanol.
The composition can contain anionic, cationic, non-ionic or amphoteri surface-active agents such as BRIJ56, BRIJ52, BRIJ58, Sodium Lauryl Sulfate and Cetrimonium Bromide.
The composition can contain, in association with the oxidation dyestuff precursors, couplers which are well known in the art. Couplers which can be used in the compositions include resorcinol and 2-methylresorcinol.
The composition can also contain reducing agents such as sodium sulfite, ascorbic acid and sodium bisulphite.
In view of the above, it is the primary objects of the invention to produce a process that when applied, in combination with one of the disclosed hair heating devices, allows hair to be efficiently dyed in a shorter time period which, in turn, mimimizes hair damage.
In addition to the primary object of the invention, it is also an object of the invention to provide a hair dyeing process and device that:
is quick and convenient,
is relatively safe,
can be used with a variety of hair color dyes,
can be used with very little training, and
is cost effective from both a manufacturing and consumer points of view.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.